The supply teaching agency rings at 8.10am. I'm about to be transformed from mild-mannered man of leisure Andy Dole, into "Supply Sir". I had plans for today - happy, selfish indulgences; magazines to flick through; a Laurel and Hardy double bill I'd circled in the television guide.
The agency's own husky-voiced Tokyo Rose starts her skilful manipulation.
I'd do anything for this temptress. Yes, I will travel the 12 tortuous miles to Slab City Comprehensive. Yes, I will report to Mr Raptor. Yes, I will be there by 10 to nine.
A terrifying panic engulfs me as I realise it is Tuesday. At Slab City Comp this could mean 8L for environmental studies. An overpowering need to go to the lavatory sets the pattern for the rest of the day.
Please do not let it be 8L, I pray, as Mr Raptor passes over my pink supply teacher's timetable. But there it is, bold and black, period 3, environmental studies, 8L. A rising tide of clammy sweat bursts like sea-water through a sand wall, soaking my deodorised armpits.
The school bell sounds and the full-timers scatter off to registration, business-like, books in hand. In the staffroom, the supplies perch nervously on the edge of low plastic seats, forlornly contemplating their pink-sheeted fates.
I retire to the solitude of the staff toilets for some ego-bolstering contemplation in front of the brown-flecked mirror. With varying degrees of conviction, I lower my eyebrows to produce stern, "I-must-be-obeyed" teacher-like looks. Then, straightening my tie and buttoning up my jacket, I pick up my case and walk past the mingling muddle of screeching truculence that inhabits the corridors of Slab to my first lesson.
By 11.30, I'm explaining to 8L that my name is Mr Dole, not Mr Hole. I raise my arm to point out the title Global Warming on the whiteboard, at the same time revealing my wet, patched shirt underneath my opening jacket.
Cooper, a face that has haunted many of my school-room nightmares, immediately squeals out with glee, 'Mr Piss-Hole!' to riotous roars.
The day continues with the ceaseless bombardments of penless pupils, paper-flicking boys and loud, gum-chewing girls, which snipe, bang and rattle away at my shell-shocked self-esteem. I finally drive out of Slab to the sight of a two-fingered farewell in my rear-view mirror.
Andy Dole is a supply teacher in south Wales. All names have been changed